Numerical Simulation Of The Two-phase Detonation And Effect Of Multi-dusts

Dust detonation is a common two-phase detonation.The dust damage caused by the warm-air weapons in the military and the dust explosion accident in the industrial sector are typical dust detonation.The type,size,and density of dust particle during dust detonation have important influence on the parameters of detonation waves.Dust detonation most occurs in complex structures in warm-air weapons and industrial safety accidents.Therefore,the effect of different factors to dust detonation,the detonation wave propagation law of dust detonation,and the effect of temperature and pressure are of great significance for the development of national defense weapons and the prevention and control of industrial safety.In this paper,the combustion reaction model of aluminum dust in the flow field is mainly improved.The influence of the dust particle size and density on the detonation wave parameters of the dust detonation in the channel is studied.The detonation wave propagation law of the dust detonation in the complex geometry space is studied.The temperature and pressure effects of the detonation waves of suspended dust cloud in free-field and complex geometry space are studied.The specific research work is as follows:1)It improves the aluminum dust combustion reaction model.When the flow field temperature is higher than the boiling point of Al₂O₃,the Al₂O₃ will be decomposed.So the temperature of flow field will not exceed the boiling point of Al₂O₃.The decomposition assumes the formation of gaseous Al and O₂.When the temperature drop is lower than the boiling point of Al₂O₃,the gaseous Al will continue to react with O₂ which we call"secondary reaction".The"secondary reaction"model is added to the numerical simulation program.2)It simulates the detonation of suspended aluminum dust in air.The influence of the radius of aluminum dust on the detonation wave parameters is studied.It is found that the pressure and velocity of detonation wave can be significantly improved after the particle size becomes smaller.The cell structure of aluminum dust detonation wave in tube is obtained.The horizontal size of cell is 0.83m when the dust concentration is 0.3kg/m³ and the radius is 4.5?m.The detonation waves of aluminum dust detonation are investigated in the two large spaces connected by channel.The density of dust is 0.304kg/m³ and the radius is 2?m.It is found that there is a local high pressure zone of 18 MPa in the left space.This is due to multiple reflections of detonation waves in the confined space.Thee velocity of detonation wave which basically reaches a stable propagation state at the outlet of the channel is 1571 m/s,and the pressure reaches 2.85 MPa.It shows that the detonation wave can gradually reach the stability through diffracting into the channel and propagate into another space through diffraction.3)The detonation of RDX-Al mixed dust suspended in air is studied.The influence of particle radius in mixed dust on the structure of detonation waves is studied.While the radius of the RDX particles is 10?m,the double-front appears when the radius of aluminum particles is larger than 2.0?m.This was due to the difference exothermicity of explosive particles and aluminum particles.The effects of different aluminum dust densities on detonation wave parameters during the detonation of suspended Al-RDX mixed dust in air are studied.After fixing the RDX dusts density,the results show that the detonation wave velocity and pressure decrease accordingly when the concentration of aluminum dust decreases,the pressuir and temperature at the CJ point decreases,and the reaction zone narrows.The process of detonation of mixed dust in a complex channel is simulated.And compared with the detonation process of aluminum dust,it is found that adding RDX dust can significantly increase the peak pressure,temperature,and detonation wave propagation velocity of the flow field.4)The effect of temperature and pressure caused by the detonation of suspended aluminum dust in the air is studied.The detonation pressure gradually increases after initiation in center.And it reaches the maximum value when reaching the edge of the cloud.Then,due to the separation of the shock wave from the dust cloud,the shock wave pressure rapidly decreases.And it forms a fireball in the center of the flow field.The maximum pressure of the flow field decreases accordingly with the concentration of dust decreasing when the particle diameter is 2mm.The shock wave velocity,the temperature of the fireball and the propagation distance of the fireball all decrease accordingly.However the oxygen volume fraction in the fireball increases.When the dust size increases,the maximum pressure in the flow field decreases,and the high temperature in the fireball continue in a larger range.While the shock wave velocity decreases.5)It studies the damage effect of suspended aluminum dust in air.The particle parameters of dust cloud are that the diameter is 2mm,the equivalence ratio is 1,and the radius of cloud is 3m.The propagation distance of the fireball formed by the cloud is 10m.The overpressure of the shock wave is 0.1MPa when it propagates to 24.5m.And it is 0.09MPa when the shock wave reaches 28m.According to the degree of damage to the human body caused by the shock wave in the experimental formula of the cloud explosion bombardment,it can be considered that it can caused death within the range of 24.5m and serious damage to the human body within the range of 24.5m to 28m.At the same time,the influence of the"secondary reaction"of aluminum on the temperature and pressure effect of the explosion of aluminum dust clouds is discussed.The results show that the"secondary reaction"of aluminum can significantly increase the temperature within the fireball.6)The damage effect of the detonation of free-field RDX-Al mixed dust in air is studied.The temperature and pressure effects of of RDX-Al mixed dust cloud and RDX dust cloud when the density is 0.71kg/m³ under the same ignition conditions are studied.The numerical simulation results show that the overpressure of the mixed dust cloud impact wave is 0.11MPa at 28m,while the shock wave of the single RDX dust cloud with the same total density is 0.095MPa at 28m.The temperature of the fireball formed by the mixed dust cloud is higher by 750K than the fireball formed by the single RDX dust cloud.It indicates that under the same quality,the effect of the temperature and pressure is greatly improved after the addition of aluminum dust.7)It simulaties the RDX-Al mixed dust detonation in air in a complex geometry space.The local high-pressure region is formed near the wall surface after the action of the shock wave generated by dust cloud detonation and the solid wall.The reflected wave is generated by the action of the shock wave and the solid wall.And a local high-pressure region is formed because of the interaction of reflected waves.The shock wave diffract in the corner area.The fireball formed by the detonation of dust clouds will also diffract in the corner area.And a low-temperature vortex is formed in the corner area.When the reflected wave interacts with the fireball,it will significantly increase the temperature of the fireball.